Coaxial reflection light is realized by a coaxial reflection illuminator. Coaxial reflection illuminator is placed horizontally, parallel to the worktable, and is at a 90 degree angle to the optical axis of the microscope. When the illumination light passes through the coaxial reflection illuminator, the light is first turned through a reflection prism or beam splitter to a 90-degree angle, and is vertically (or nearly vertical) irradiated onto the surface of the object to be observed, and then reflected back to enter into the eyepiece through the objective lens.
The coaxial reflected light is suitable for illuminating planar objects and objects with high reflectivity. In addition, when the opaque or translucent objects are observed by large magnification objective lens, if the working distance is too short and an external light source cannot be used, the coaxial reflected light may be the best and the only choice.
Coaxial reflection illuminator, usually consisting of illumination light source, lamp chamber, condenser lens, aperture diaphragm and field diaphragm, color filter converter, and heat sink etc., achieves light emission and control.
The light or lamp chamber is generally made of a metal shell, with a ventilating vent or heat sink on the outside, but does not leak light, and has a spiral or top wire mechanism for adjusting the light axis.
Light source filament position and coaxial adjustment of the center of the optical axis
Because the illumination source is modularized with the microscope body and also, when in use, due to movement operation etc., the position of the filament of the illumination source and the illumination optical axis often deviate, which causes the Kohler illumination system to be damaged, thereby affecting the brightness of the field of view and the uniformity of illumination.
The main reason that affects the uniformity of illumination is that the position of the filament of the light source is not on the optical axis, which makes the field of view appear uneven. The main reason that affects the brightness of the field of view is that, after passing through the condenser for condensation, the illumination light is not focused on the aperture diaphragm plane.
The above therefore needs to adjust the position of the bulb in the coaxial reflection illuminator. Firstly, by adjusting the positioning screw on the light source, change the position of the lamp holder, and adjust the illumination bulb up and down, left and right, so that the filament is located on the optical axis of the center. Then, loosen the fixing screws on the condenser, move the condenser back and forth, so that the illumination light will converge at the center of the aperture diaphragm, and then tighten the screws. This not only makes the illumination in the field of view the brightest, but also uniform, and has no filament image.
Some metallurgical microscopes are equipped with "light chamber adjustment objective lens". When using, first remove an objective lens, rotate the light chamber adjustment objective lens into the nosepiece, and transfer it into the imaging light path, and replace the objective lens for the above adjustment.
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